energies

Communication Proposal for an Experimental Methodology for Evaluation of Natural Systems Applied in Buildings

Anderson Diogo Spacek 1, João Mota Neto 1, Luciano Dagostin Biléssimo 1, Oswaldo Hideo Ando Junior 2,*, Gustavo Pedro De Freitas Neto 1, Rodrigo Da Silva Giansella 1, Marcus Vinícius Ferreira De Santana 3 and Celia De Fraga Malfatti 4

1 Department of Mechanic and Automation, SATC, Beneficent Association of Santa Catarina Coal Industry, Street Pascoal Meller, 73, Criciúma-SC CEP 88805-380, Brazil; [email protected] (A.D.S.); [email protected] (J.M.N.); [email protected] (L.D.B.); [email protected] (G.P.D.F.N.); [email protected] (R.D.S.G.) 2 Department of Renewable Energies, UNILA, Federal University of Latin American Integration, Av. Sílvio Américo Sasdelli, 1842, Foz do Iguaçu-PR CEP 85866-000, Brazil 3 Hidroelectric Power Plant, BAESA, Energética Barra Grande S/A, Street Madre Benvenuta, 1168, Florianópolis-SC CEP 88035-000, Brazil; [email protected] 4 Corrosion Research Department, Federal University of Rio Grande do Sul, Avenue Bento Gonçalves, 9500, Porto Alegre-RS CEP 91501-970, Brazil; [email protected] * Correspondence: [email protected]; Tel.: +55-045-3529-2138

Received: 11 May 2017; Accepted: 27 June 2017; Published: 17 July 2017

Abstract: This work has the objective of developing a methodology for the evaluation of indoor natural lighting systems, which, with speed and practicality, provides from real conditions of use a reliable result about the quality and performance of the proposed system. The methodology is based on the construction of two real-size test environments, which will be subjected to a natural light system through reflexive tubes made from recycled material, and to a commercial system already certified and consolidated, creating the possibility of comparison. Furthermore, the data acquired in the test environments will be examined in light of the values of solar radiation obtained from a digital meteorological station, such that it is possible to stipulate the lighting capacity of the systems at different times of the year.

Keywords: ; solar radiation; ; solar energy harvesting; green energy; measurement

1. Introduction According to data from the Energy Research Company, the consumption of electric energy in Brazil will be growing by 3.7% per year by 2030. For this reason, it is necessary to constantly increase the energy supply and development of systems with higher efficiency to accompany the increased consumption of electrical energy. Besides this indicator, it is observed that the Brazilian territory is geographically between the line of the Equator and the Tropic of Capricorn, and, therefore, presents high solar incidence throughout the year [1]. Brazil has territorial characteristics that contain a solar incidence of around 8 to 22 mega joules per square meter [2], this solar radiation is superior to the majority of Europe, where the solar system is used for residential lighting. Germany applies the use of solar energy in the generation of electricity on a large scale, although it presents solar radiation indices around 40% lower than those in the Southern Region of Brazil, which has the worst index, indicating a great potential for solar exploitation in Brazil [3,4].

Energies 2017, 10, 1014; doi:10.3390/en10071014 www.mdpi.com/journal/energies Energies 2017, 10, 1014 2 of 12

Analyzing the structure of electricity consumption among the classes, it is observed that the commercial class shows the highest growth in the period 2015–2020, at 4.4% per year, followed by other classes (4.0% per year), residential class (3.8% per year) and industrial (2.5% per year) [3]. The evolution of residential electricity consumption in Brazil in the last decade can be seen as the combined effect of an average growth of 2.5% per year in the number of new consumers connected in the electricity grid. This has occurred due to investments in infrastructure promoted by the government, social programs and an average growth of 1.3% per year in consumption per residential consumer [3]. The residential sector represents a significant portion of total electricity consumption in the country. The sector represents 25% of total electricity consumption, according to the latest National Energy Balance, behind only the industrial sector [4]. Another relevant impact of residential consumption on the interconnected system of Brazilian electricity is due to the change in consumption peaks during the summer, changing the peaks from 6:00 p.m. to 3:00 p.m., approximately. This change is due to two main aspects, related to the lighting systems and the significant increase of climatization of residential environments. In this scenario, studies aimed at efficiency, reduction of lighting consumption and new sources of clean energy are essential to avoiding, in the medium and long terms, electricity rationing and/or the collapse of the electricity supply system [4,5]. Among the possible solutions for application in homes and commercial environments is the capture of and its redirection to interior environments as an alternative to the use of lamps. However, the efficiency of lighting through solar radiation is linked to climatic conditions [6]. The conventional solution for the use of natural lighting through window openings, when used alone, results in uneven distribution in indoor environments, causing excessive illumination near the aperture—and, consequently, problems—and insufficient levels of illumination at distant points. This conventional method generates overheating at places near the opening and results in an increase in the consumption of electric energy in the building for cooling [7]. To solve these problems, systems have been developed that take better advantage of natural light, mainly devices that redirect light, such as prismatic materials, light shelves, light ducts, etc. Simple systems for harnessing solar radiation for indoor lighting are called zenith systems. The use of lighting through zenith openings allows a greater uniformity of distribution of natural light compared to lateral illumination and, importantly, allows higher levels of illumination on the work plane. Among the devices that comprise this solution are the translucent tile, , shedé, lantermin and domes [8]. Advanced natural lighting systems have emerged as a means of reducing the negative effects of natural lighting and improving the performance of buildings in terms of natural daylight and energy efficiency, while at the same time gaining greater control of the direct solar radiation input. In the devices that make up advanced systems, the reflexive tube responsible for the redirection of the natural light to poorly-illuminated zones, and for the improvement of visual comfort, stands out. The study of Soto (2010) evaluated the capacity of natural light to be obtained and distributed through light tubes in order to generate adequate lighting in popular habitation. A result was obtained in which it could reach a savings of 38% in the economic cost of energy used in artificial lighting for the simulated days, in addition to a possible improvement in the environmental quality of low-cost habitation [9]. Li et al. (2010) developed a study in Hong Kong to determine the efficiency of a . In this study, 10 light tubes were installed in the ceiling of a hall, the results showed that the system, when integrated with an adequate lighting control, can substantially reduce the energy consumption of lighting [10]. With the objective of evaluating the efficiency of solar tubes, a 1:1 scale solar tube model was developed to determine the efficiency of light conduction, taking into consideration the reflectance and transmittance of the elements and their materials. This study shows that the main contribution of this system is to provide light to the deeper and less illuminated areas of buildings, and significantly improve the visual comfort of people [11]. In addition, regarding the capture of solar radiation on the Energies 2017, 10, 1014 3 of 12 roof of the building, the length of the reflective tube can be varied to provide illumination to the desired internal environment. This fact makes the study of the reflective tube relevant in the determination of implantation costs, since high value materials are generally employed in the fabrication of this mechanical component, and, consequently, it negatively affects the payback of the substitution of artificial lighting by natural lighting. The use of solar tubes for ambient lighting began in 1986, when an Australian inventor presented an innovation in lighting the interior of environments. The invention was patented by the company SOLATUBE, which began to act in the commercialization of the product. The product has evolved over the years, reaching maximum possible yield [12]. Over the years, competing companies have come up offering similar products based on the original design, but with small changes in the materials used, as can be seen in Table1.

Table 1. Commercial Reflective Tubes.

Manufacturer Reflective Tube Material Nominal Reflection Espacio Solar (Spain) Aluminum with silver coating 98% Velux (Portugal) Highly reflective aluminum 99% Fakro (Portugal) Aluminum with silver coating 98% Natural light tubular skylights (USA) Aluminum with silver coating 98% SOLATUBE (Australia) Aluminum with silver coating 99.7% Chatron (Portugal) Aluminum with silver coating 99.7% Solarspot (Italy) Highly reflective aluminum 99.7%

At the research level, there are some studies on tubular natural light systems, which are presented in Table2.

Table 2. Research developed.

Title Information Evaluation of reflectivity in solar tubes from integrative Cylindrical light pipes [13] sphere analysis Tubular guidance systems for daylight: Achieved and predicted Critical review of existing zenith lighting methods installation performances [14] Tubular light guidance systems as advanced Evaluation of tubular lighting systems using SkyVision software strategy [15] and other software with the same function Rectangular-section mirror light pipes [16] Modeling of rectangular reflective systems with integrative sphere Analytical solution for daylight transmission via hollow light Modeling of light transmission in solar tubes pipes with a transparent glazing [17] Splayed mirror light pipes [18] Modeling of rectangular reflective systems Definition of expressions for calculation of light transmission in Transmission of mirror light pipes with triangular, rectangular, reflective, triangular, rhombohedral and hexagonal rhombic and hexagonal cross section [19] rectangular systems Overview and new developments in optical daylighting systems Overview of two optical natural lighting systems (tube light for building a healthy indoor environment [20] systems and mirror systems) Light transmission efficiency of daylight guidance systems: Characterization of the photometric performance of tubular light An assessment approach based on simulations and measurements guidance systems in terms of light in a sun/sky simulator [21] Light Pipes Performance Prediction: inter model and experimental Modeling and experimental analysis of vertical solar tubes confrontation on vertical circular light-guides [22] Study of light-pipes for the use of sunlight in road tunnels: Evaluation of the application of light tubes in tunnel lighting From a scale model to real tunnels [23] Thermal analysis of light pipes for insulated flat roofs [24] Thermal analysis of solar tubes used in roofs Innovative daylighting systems challenges: A critical study [25] Analysis of existing natural light utilization technologies Presentation of a model for evaluating the efficiency of Research on energy saving analysis of tubular daylight devices [26] tubular systems Investigation of laminar natural convection heat transfer within Experimental and numerical study on natural laminar convection tubular daylighting devices for winter conditions [27] in TDD for winter conditions Passive Tubular Daylight Guidance System Survey [28] Case study of the installation of a TDGS in Cluj-Napoca (Romania) Study of tubular daylight guide systems in buildings: Proposition of a new model of analysis more precise to validate Experimentation, modelling and validation [29] the TDGS in efficacies Energies 2017, 10, 1014 4 of 12

This work describes the use of a test environment built for the validation of solar tubes using recycled polymers with internal aluminum vacuum metallization to ensure the necessary reflexivity. These tubes proposed for validation seek to present an alternative to commercial products that use as materials aluminum metallized with high-purity silver, which makes the production cost too high for large-scale application.

2. Materials and Methods The standards regulating internal lighting in residential and commercial environments that were applied in this study, ABNT NBR ISO-CIE 8995-1, have been in force in Brazil since 2013. This norm defines the levels of adequate illuminance within of the workplace in order to ensure the health and integrity of the users of the room, and thus allow them to perform activities such as writing, reading and drawing [30]. In the regulatory standard, it is possible to find the parameter definitions in order to perform a calculation mesh for the design of a lighting system and, with the aid of luminosity measurement equipment (lux meters), determine the average illuminance and the uniformity of the incident light [30]. In order to carry out the calculations, it is necessary to know the largest dimension of the surface to be measured. The room in question was rectangular and had dimensions of 3 wide by 4 long, so its largest dimension (D) is approximately 5 m. The mesh size (P) is determined based on Formula (1), in meters [30]. P = 0.2 × 5log10D (1)

The number of points to be measured was determined through Equation (1), with 8 lux meters being required in each room, but during the period in which the study was performed only 6 were available. This, however, didn’t interfere with the proportionality of measurement and data collection, since the equipment was evenly distributed on the surface and, consequently, the resulting illuminance of the environments could be obtained through the average data acquired through the devices.

2.1. Characteristics of Natural Lighting Systems Advanced indoor natural lighting systems, as shown in Figure1, are basically composed of three components. The dome is responsible for capturing the external solar radiation and for redirecting into the reflective tube, which has the function of conducting the luminosity to the desired location for illumination of the internal environment. Finally, the diffuser has the function of homogenously distributing the illumination in the environment. Therefore, the test environment proposed in this study allowed the individual comparative tests of the three components applied in the use of natural light and, consequently, made it possible to evaluate the impact of each component related to the overall lighting efficiency of the system. In order to evaluate the efficiency of the redirection of solar radiation by the proposed reflective tube compared to commercially available options, it was decided to use domes with Fresnel lenses in the two systems of capture of solar radiation. This allowed greater concentration of illumination, regardless of the position of the sun, and diffusers composed by prismatic lens in which the illumination is diffused homogeneously in the environment. Consequently, the comparative analysis was concentrated on the efficiency related to the performance of the tube, and the number of study variables was reduced. Energies 2017, 10, 1014 5 of 12 Energies 2017, 10, 1014 5 of 12 Energies 2017, 10, 1014 5 of 12

Figure 1. Representation of a lighting system with reflective tube. Figure 1. Representation of a lighting system with reflective tube. Figure 1. Representation of a lighting system with reflective tube. Because of the variety of solar tubes available on the market, and the manufacturing process of theseBecause Becauseproducts ofof is the an variety important of solar solar factor tubes tubes in available availablethe impa onct on theof the performance, market, market, and and thewe the manufacturing searched manufacturing for lower-cost process process of ofalternativesthese these products products to manufacture is isan an important important the solar factor factor tubes. in in theTheref the impa impactore,ct theof of performance,prototype of the we tube searched was produced forfor lower-costlower-cost using alternativesaalternatives small plastic toto manufacturemanufacture injection molding the the solar solar tubes.machine tubes. Therefore, Theref for ore,large-scale the the prototype prototype production of of the the tube tubewithout was was produced producedburdening using using the a smalldesigna small plastic with plastic injectionthe injectionnecessity molding molding for machine high-capacity machine for large-scale forequipment. large-scale production The production prototype without burdening withoutof the tube theburdening designhas a total with the thelengthdesign necessity ofwith 1800 forthe mm, high-capacity necessity being formedfor equipment. high-capacity from tubes The equipment. prototype of 100 mm of The thein length. tubeprototype has Table a totalof 1the lengthpresents tube of has 1800the a main mm,total beingconstructivelength formed of 1800 characteristics from mm, tubes being of 100 offormed the mm two in from length.solar tubes tubes Table of implemented1 100presents mm thein inlength. main the test constructive Table environment, 1 presents characteristics which the mainhave of theconstructive twopurpose solar of tubescharacteristics evaluating implemented the of efficiencythe in two the solar test of the environment,tubes internal implemented lighting which in haveof thethe thetest environment purposeenvironment, of compared evaluating which haveto the a efficiencycommercialthe purpose of system. theof evaluating internal lighting the efficiency of the environment of the internal compared lighting to of a commercialthe environment system. compared to a commercialThe commercial system. lighting system used for the co comparativemparative study was a SOLATUBE model 160DS (SOLATUBE,The commercial Spokane,Spokane, lighting WA, WA, USA), systemUSA), 250 used mm250 for inmm diameter, the in co dimparativeameter, constructed constructedstudy of was 99% a aluminumSOLATUBEof 99% aluminum and model metallized 160DS and internallymetallized(SOLATUBE, with internally Spokane, silver ofwith high WA, silver purity. USA), of high The 250 prototypepurity. mm Thein asdi prototype mentionedameter, constructed as above mentioned was developedof above99% wasaluminum with developed recycled and polypropylene,withmetallized recycled internally polypropylene, internally with metallized silver internally of high with metalliz purity. aluminum edThe with throughprototype aluminum the as process mentioned through of vacuum the above process metallization was ofdeveloped vacuum by themetallizationwith magnetron recycled by sputteringpolypropylene, the magnetron process. internally sputtering As can bemetalliz process. seen ined FigureAs with can 2aluminum ,be due seen to the in throughFigure limitations 2, the due ofprocess to the the metallization limitationsof vacuum process,ofmetallization the metallization it was by necessary the process, magnetron to construct it was sputtering necessary the tube process. to in construct parts, As in can thisthe be casetube seen semi-tubesin in pa Figurerts, in by2,this due the case injectionto thesemi-tubes limitations process, by sotheof the thatinjection metallization they process, could beprocess, so metallized that theyit was could internally necessary be metalliz andto construct subsequentlyed internally the tube and form in subsequently pa therts, reflective in this formcase tube. semi-tubes the Afterreflective the by metallizationtube.the injection After the process, of metallization these so semi-tubes, that theyof these could rings semi-tubes, be were metalliz constructed riedngs internally were which constructed and were subsequently then which joined were form to thethen the tube joinedreflective in the to desiredthetube. tube After length. in the the desired metallization length. of these semi-tubes, rings were constructed which were then joined to the tube in the desired length.

Figure 2. Prototype of the proposed system. Figure 2. Prototype of the proposed system. Figure 2. Prototype of the proposed system.

Energies 2017, 10, 1014 6 of 12 Energies 2017, 10, 1014 6 of 12 Energies 2017, 10, 1014 6 of 12 The Table3 3 presents presents a a comparison comparison between between the the proposed proposed system system and and a a commercial commercial luminaire. luminaire. The Table 3 presents a comparison between the proposed system and a commercial luminaire. Table 3. Main features of reflectivereflective tubes. Table 3. Main features of reflective tubes. Characteristics of Reflexive Tubes CharacteristicsCharacteristics ofof ReflexiveReflexive Tubes DiameterTubes Length Weight External Material Internal Material External Material Internal Material Diameter (mm)Diameter(mm) Length (mm)Length(mm) Weight Weight(Kg) (Kg) External Material Internal Material CommercialCommercial High-purityHigh-purity silver silver (mm) (mm) (Kg) AluminumAluminum 99% 99% 250250 18001800 2,2 2.2 (Solatube(SolatubeCommercial 160DS) 160DS) (Vacuum Metallization)(VacuumHigh-purity Metallization) silver RecycledAluminum 99% Aluminum 250 1800 2,2 (SolatubePrototype 160DS) (VacuumAluminum Metallization) 250 1800 2.9 Prototype polypropyleneRecycled polypropylene(Vacuum Metallization) 250 1800 2,9 (VacuumAluminum Metallization) Prototype Recycled polypropylene 250 1800 2,9 (Vacuum Metallization) 2.2. Validation System 2.2. Validation System The proposed experimental model consists of two rectangular rooms of the same dimensions, completelyThe proposed enclosed experimental so that there model is no interference consists of oftwo unwanted rectangular solar rooms radiation, of the thus same ensuring dimensions, that thecompletely results come enclosed exclusively so that therefrom isthe no objects interference of of st study.udy. of unwantedFigure Figure 33 showsshows solar theradiation,the layoutlayout thus ofof thethe ensuring luxlux meter,meter, that dimensions,the results come diffusersdiffuser exclusivelys and their from respective the objects diameters.diameters. of study. Figure 3 shows the layout of the lux meter, dimensions, diffusers and their respective diameters.

Figure 3. Representational layout of the elements that make up the test environment. Figure 3. Representational layout of the elements that make up the test environment. Figure 4 shows the installation of the reflective tubes responsible for directing the illumination Figure4 shows the installation of the reflective tubes responsible for directing the illumination capturedFigure through 4 shows collectors the installation located onof thethe reflectiveroof of the tubes test responsibleenvironment, for and directing distributed the illumination inside the captured through collectors located on the roof of the test environment, and distributed inside the roomscaptured through through diffusers collectors located located in the on center the roof of each of the room. test environment, and distributed inside the roomsrooms throughthrough diffusersdiffusers located located in in the the center center of of each each room. room.

Figure 4. Arrangement of the reflective tubes in the test environment. Figure 4. Arrangement of the reflective tubes in the test environment. Figure 4. Arrangement of the reflective tubes in the test environment. This constructive way of fixing the reflective tubes allows a quick and convenient replacement of theThis tubes constructive to make other way comparisons of fixing the in reflective order to tubesidentify allows materials a quick that and pr esentconvenient a higher replacement reflection indexof theThis and, tubes constructive consequently, to make other way helps comparisons of fixing to raise the the reflectivein internalorder to tubes illuminationidentify allows materials a indices quick that andto prmeet convenientesent the a currenthigher replacement reflectionnorms. ofindex the tubesand, consequently, to make other helps comparisons to raise the in order internal to identify illumination materials indices that to present meet the a highercurrent reflection norms. index2.3. Data and, Acquisition consequently, helps to raise the internal illumination indices to meet the current norms. 2.3. Data Acquisition In order to acquire the data concerning the internal lighting of the two rooms that make up the test, MLM-1020In order to luxacquire meter the (Minipa, data concerning São Paulo, the Brazil) internal was lighting used, ofwhich the two was rooms designed that withmake a up basic the test, MLM-1020 lux meter (Minipa, São Paulo, Brazil) was used, which was designed with a basic

Energies 2017, 10, 1014 7 of 12

2.3. Data Acquisition

EnergiesIn 2017 order, 10, to 1014 acquire the data concerning the internal lighting of the two rooms that make up the7 of test, 12 MLM-1020 lux meter (Minipa, São Paulo, Brazil) was used, which was designed with a basic precision precisionof 3 percent, of 3 and percent, a datalogger and a datalogger system with system a capacity with of a2044 capacity data. of Data 2044 for data. global Data solar for radiation global solar was radiationobtained throughwas obtained the Digital through Vantage the Digital Pro 2 Vantage meteorological Pro 2 meteorological station (Davis Instruments,station (Davis Hayward, Instruments, CA, Hayward,USA), in the CA, period USA), between in the period January between and December, January 2016.and December, The meteorological 2016. The stationmeteorological was installed station in wasthe collegeinstalled SATC in the (Crici collegeúma, Brazil),SATC (Criciúma, and made itBraz possibleil), and to analyzemade it thepossible global to radiation analyze in the the global south ◦ ◦ radiationof state of in Santa the south Catarina of state (Brazil) of Santa at the Catarina following (Brazil) coordinates: at the following 28.4 S 49.12coordinates:W and 28.4° 32 m S above 49.12° the W andsea level.32 m above the sea level.

3. Results and Discussion The stationstation performed performed data data recording recording throughout througho theut 24 the h of 24 the h day, of andthe dueday, to thisand characteristic,due to this characteristic,it was defined it that was the defined daily that period the ofdaily analysis period will of analysis include thewill interval include fromthe interval 8:00 a.m. from to 8:00 a.m. p.m. toData 8:00 on p.m. sunlight Data outsideon sunlight this timeoutside interval this time were in foundterval towere be irrelevantfound to be for irrelevant the purposes for the of thispurposes study. ofThrough this study. the analysis Through of the the analysis obtained of values, the obtained the efficiency values, of the the efficiency reflective tubesof the thatreflective make uptubes the that test makeenvironment up the test was environment verified and, was consequently, verified and, a comparative consequently, analysis a comparative between analysis the two systemsbetween wasthe tworealized, systems making was it realized, possible tomaking define theit possible rate of transmission to define the of rate the externalof transmission luminosity ofto the the external interior luminosityfor the developed to the interior recycled for tube the in developed comparison recycled to the tube commercial in comparison tube. to the commercial tube. With the help of the data obtained by the digitaldigital meteorological station during 2016, it was possible to be aware of the variation of the solar ra radiationdiation incidence during the the year, year, as well as to stipulate a characteristic day of each month, as demonstrated below in Figure 55,, whichwhich representsrepresents anan average day that characterizes all solar incidence of the year of 2016. The main reason for developing a systems validationvalidation methodology in a testing environment is to obtain the quality of the product in question a accuratelyccurately and under real conditions, and to gain an approximate understandingunderstanding of of how how the the room room will will behave behave during during the yearthe whenyear when compared compared with values with valuespreviously previously obtained obtained from the from solar station.the solar For station. this, with Forthe this, lux with meters the proportionally lux meters proportionally distributed at distributedthe height of at the the work height plane, of the data work of illuminanceplane, data inof luxilluminance were collected in lux and were analyzed. collected It and is noteworthy analyzed. Itthat is noteworthy the data acquisitions that the data were acquisitions carried out were during carried the summer,out during over the ten summer, days, at over the ten end days, of January at the endand of beginning January ofand February. beginning of February.

Figure 5. Annual average global radiation of 2016, from 06:00 to 20:00 h. Figure 5. Annual average global radiation of 2016, from 06:00 to 20:00 h. Throughout the period of tests and measurements, there was no interference from users inside the room,Throughout with natural the period light being of tests the and only measurements, source of incident there light was captured no interference in the environment. from users insideFrom Tablesthe room, 4 and with 5, naturalit is possible light beingto verify the the only averag sourcee ofdata incident acquisition light capturedfor each hour in the during environment. the ten days, From both from the rooms with the commercial system and the prototype system, measured in lux, and of the meteorological station, measured in Watt/m2.

Energies 2017, 10, 1014 8 of 12

Tables4 and5, it is possible to verify the average data acquisition for each hour during the ten days, both from the rooms with the commercial system and the prototype system, measured in lux, and of the meteorological station, measured in Watt/m2. Energies 2017, 10, 1014 8 of 12 Table 4. Values obtained from the analysis of the luminosity in the test environments and in the meteorologicalTable 4. Values station—Part obtained from 1. the analysis of the luminosity in the test environments and in the meteorological station—Part 1. Hour 06:00 07:00 08:00 09:00 10:00 11:00 12:00 Hour 06:00 07:00 08:00 09:00 10:00 11:00 12:00 Standard Tube 0.00 4.11 19.85 44.45 57.82 81.18 97.99 RecycleStandard Tube Tube 0.00 0.00 1.55 4.11 5.7019.85 44.45 12.75 57.82 17.91 81.18 27.9497.99 38.39 Solar Rad.Recycle Tube 0.60 0.00 31.70 1.55 119.30 5.70 12.75260.80 17.91 326.30 27.94 350.90 38.39 390.10 Solar Rad. 0.60 31.70 119.30 260.80 326.30 350.90 390.10 Table 5. Values obtained from the analysis of the luminosity in the test environments and in the meteorologicalTable 5. Values station—Part obtained from 2. the analysis of the luminosity in the test environments and in the meteorological station—Part 2. Hour 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 Hour 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 StandardStandard Tube Tube 77.60 77.60 90.5790.57 78.6478.64 50.6250.62 29.8929.89 23.9723.97 10.43 10.43 0.46 0.46 Recycle Tube 41.02 39.50 29.32 18.05 10.24 7.70 3.61 0.16 Recycle Tube 41.02 39.50 29.32 18.05 10.24 7.70 3.61 0.16 Solar Rad. 430.90 438.30 401.70 294.20 246.40 147.90 66.50 13.50 Solar Rad. 430.90 438.30 401.70 294.20 246.40 147.90 66.50 13.50

Based on studies performed previously, and on the table developed, it is possible to relate the values obtained in the two environments, and deducededuce with certainty that the tube produced with recycled material material has has an an efficiency efficiency of of approximat approximatelyely 40% 40% when when compared compared to tothe the commercial commercial tube tube (in (inwhich which it presents it presents 99% 99% reflection), reflection), as asshown shown in inTables Tables 44 andand 55 However,However, withwith thethe objective objective of of simulating the the annual annual lighting lighting curve curve of of 2016 2016 that that the the two two environments environments were were supposed supposed to have, to have, two twographs graphs which which relate relate the incidence the incidence of solar of solar radiation radiation to the to variation the variation of illuminance of illuminance inside inside the test the testenvironment environment were were produced. produced. It is It known is known that that wi withinthin the the spectrum spectrum of of sunlight, sunlight, a a large large portion represents visible visible light light (between (between 370 370 and and 750 750 nm), nm), which which will will be beused used in the in the system system to illuminate to illuminate the theinternal internal environment environment [31], [31 and], and that that global global solar solar radiation radiation is isnot not directly directly connected connected to to internal environment illumination but, but, as determined through through the the measurements measurements shown shown in in Figures Figures 6 andand7 7,, that thethe variations variations of of these these physical physical quantities quantities are proportional; are proportional; i.e., when i.e., the when solar the radiation solar increases,radiation theincreases, visible the luminosity visible luminosity is also greater. is also greater.

Figure 6. Relation between solar radiation and internal luminosity of the test room in which it has Figure 6. Relation between solar radiation and internal luminosity of the test room in which it has commercial pipe. commercial pipe.

Energies 2017, 10, 1014 9 of 12 Energies 2017, 10, 1014 9 of 12

Energies 2017, 10, 1014 9 of 12

Figure 7. Relation between solar radiation and internal luminosity of the test room in which it has Figure 7. Relation between solar radiation and internal luminosity of the test room in which it has prototype pipe. prototypeFigure pipe. 7. Relation between solar radiation and internal luminosity of the test room in which it has Basedprototype on the pipe. graphs above, a mathematical conversion function was developed, responsible for transformingBased on the solar graphs radiation above, values a mathematical as read by the conversion meteorological function station was into developed, lux values that responsible will for transformingilluminateBased the on test solar the rooms. graphs radiation With above, this, values a mathematicalit was as possible read by conversion to the represent meteorological function the illumination was station developed, of intothe roomsresponsible lux values during for that transforming solar radiation values as read by the meteorological station into lux values that will willthe illuminate year, ensuring the test a rooms.wide system With this,analysis it was from possible a few days to represent of testing. the It illumination is known that of thesuch rooms a illuminate the test rooms. With this, it was possible to represent the illumination of the rooms during duringmethodology the year, ensuringwill not be a completely wide system accurate, analysis since from it does a few not days consider of testing. the natural It is knownwear and that tear such the year, ensuring a wide system analysis from a few days of testing. It is known that such a a methodologythat the systems will notwould be completelyhave. Furthermore, accurate, no since luminosity it does data not considercollection the tests natural were wearperformed and tear duringmethodology the winter will to not verify be completely or not the accurate,real proportionality since it does of not the considersolar radiation the natural in relation wear and to the tear that the systems would have. Furthermore, no luminosity data collection tests were performed during illumination.that the systems We intend would to have.perform Furthermore, new comparisons no luminosity over larger data periods collection and testsat different were performed times of the winter to verify or not the real proportionality of the solar radiation in relation to the illumination. theduring year. the winter to verify or not the real proportionality of the solar radiation in relation to the We intendillumination.Despite to perform the We limitations intend new comparisons to of perform evaluation new over of comparisons largerthe methodology periods over and larger developed, at differentperiods it isand times possible, at different of the as shown year. times in of FigureDespitethe year. 8, to the safely limitations promote of the evaluation representation of the of methodology the daily performance developed, that itthe is system possible, will as usually shown in Figureprovide.8, toDespite safely It is emphasized the promote limitations the that representation ofthe evaluation average global of ofthe thera methodologydiation daily performancein the developed, afternoon that periodit is the possible, systemis significant, as will shown usuallyand in provide.isFigure in agreement It is 8, emphasized to safely with promote the that peaks the the averageof representation electricity global cons radiationofumption the daily induring performance the afternoon the summer. that period the This system is fact significant, representswill usually and is in agreementtheprovide. initial viabilityIt with is emphasized the for peaks the implementation ofthat electricity the average consumption of global a natural radiation light during systemin the the afternoon composed summer. period of This reflective is fact significant, represents tubes. and the initialis viability inIt agreementwas observed for the with implementation through the peaks thermal of electricity ofreadings a natural cons with lightumption a pyrometer system during composed that the the summer. internal of reflective Thistest environmentsfact tubes. represents the initial viability for the implementation of a natural light system composed of reflective tubes. withIt was both observed tubes did through not contribute thermal readingsto the heat withing aof pyrometer the test room, that the and internal consequently test environments did not It was observed through thermal readings with a pyrometer that the internal test environments withnegatively both tubes impact did not the contribute thermal comfort to the of heating the environment. of the test This room, fact and is attributed consequently to the did characteristics not negatively with both tubes did not contribute to the heating of the test room, and consequently did not impactof the the material thermal applied comfort in the of confection the environment. of the domes This that fact present is attributed to theprotection. characteristics of the negatively impact the thermal comfort of the environment. This fact is attributed to the characteristics materialof the applied material in applied the confection in the confection of the domes of the that domes present that present ultraviolet ultraviolet protection. protection. 120 Commercial room Recycle room

100120 Commercial room Recycle room

80100

6080

4060 Luminosity in lux 2040 Luminosity in lux 020 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Hour 0 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Figure 8. Luminosity expected for the test Hourenvironments in 2016, from 06:00 to 20:00 h.

Figure 8. Luminosity expected for the test environments in 2016, from 06:00 to 20:00 h. Figure 8. Luminosity expected for the test environments in 2016, from 06:00 to 20:00 h.

Energies 2017, 10, 1014 10 of 12

4. Conclusions The purpose of this study was to evaluate, in a practical and fast way, the feasibility of new indoor lighting projects, especially regarding the use of natural light as a source of light in hybrid systems, in order to save electricity. It was then possible to establish a situation of real conditions, and to simulate the behavior of the system when compared to products already marketed, as well as to relate the two solutions to the meteorological station of the institution. In this conception, we reduced the inputs involved in the possible formulation of the recycled materials, which present better characteristics of light energy targeting, looking for gains in the performance of the hybrid lighting system. Thus, it was possible to estimate the quality of the system in the test phase, and to compare it with a product that had already been validated, contemplating the proposed changes with less onerousness and greater agility in obtaining the results. Sunlight is present only during one period of the day, and even then, in some cases, it is covered by clouds. Therefore, it is necessary to use artificial light to either replace or complement natural light. Even so, the system is fully feasible for residential environments because, as previously mentioned, the natural lighting coming from windows and doors can bring problems of excess heat and also great glare. The system is even more interesting for commercial, industrial, classroom, sports gymnasiums and others. In these cases, artificial light supplementation during the day is necessary, given the inefficiency of natural zenith lighting. It is concluded, therefore, that tubular illumination ensures adequately distributed illumination within the environment by reducing the consumption of electricity, and if applied on a large scale, will represent a considerable reduction in overall energy consumption and support preservation of natural resources. The proposed luminaire can be enhanced with photovoltaic systems and artificial lighting with LEDs. In this case, a photovoltaic panel carries a battery during periods of sunshine and in periods of absence of the sun, the battery provides electricity to the LEDs incorporated into the luminaire diffuser. In this case, the system could be totally off-grid, not needing the consumption of electrical energy, making the product even more attractive economically.

Acknowledgments: This project was developed under the BAESA e ENERCAN program “Research and Development”, regulated by ANEEL (3936-3314/2015). The authors would like to thank BAESA and ENERCAN for support and facilities. The present project is in the phase of registration of intellectual property in the INPI (National Institute of Industrial Property) with the number BR1020170133362. Author Contributions: A.D.S. Research on the plastic materials for the substrate and the type of material for the metallization, participated in the writing of the paper; J.M.N. Design and design of the infrastructure and methodology for validation, participated in the writing of the paper; L.D.B. Design and manufacture of reflective tube matrices, participated in paper writing; O.H.A.J. Research on the plastic materials for the substrate and the type of material for metallization; Participated in the writing of the paper; G.P.D.F.N. Writing paper; Application of data validation and treatment methodology; R.D.S.G. Application of data validation and treatment methodology; Participated in the writing of the paper; M.V.F.D.S. Participation in project design and technical feasibility; C.D.F.M. Consulting in the area of metallic and plastic materials for tube design. Conflicts of Interest: The authors declare no conflict of interest.

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